Process for the safe storing of liquid acetylene solutions



Feb. 28, 1961 O. K- NISSEN ET AI.

PROCESS FOR THE SAFE STORING OF LIQUID ACETYLENE SOLUTIONS Filed 001;. 18, 1955 00000000v- 00000000000 0000000000 .Y'Zt'i'i Fig. 4

(US/(AR K. N/SSEN MOR/TZ M/I/ER HANS WE/LER INVENTORS BY MW m ATTORN EYS United States Patent PROCESS FOR THE SAFE STORING OF LIQUID ACETYLENE SOLUTIONS Oskar K. Nissen and Moritz Maier, Frankfurt am Main, and Hans Weiler, Hofheim, Germany, assignors to Knapsack Griesheim Aktiengesellschaft, Knapsack Bezirk Koln, Germany, a company of Germany Filed Oct. 18, 1955, Ser. No. 541,261

Claims priority, application Germany Oct. 18, 1954 6 Claims. (Cl. 206-.7)

The present invention relates to a process for the safe storing and transporting of acetylene which has been mixed in the liquid phase and practically without application of pressure with a suitable substance or mixture of substances to yield a homogeneous liquid solution of low temperature. The solution so obtained is stored at boiling temperature in heat insulating containers.

We have found that acetylene solutions of the above mentioned kind which have been cooled to a temperature below their boiling points at a pressure of 760 millimeters of mercury can be stored under a protective gas, preferably nitrogen, in stationary or portable containers insulated in the best possible way against the influence of temperature. As protective gases, other gases can also be used, for example, argon, helium, neon, krypton, xenon or methane. The total pressure of the gases and vapors must be at least equal to the atmospheric pressure. The container, especially the vapor-space above the low-temperature acetylene solution, is partially or totally filled with some suitable material which is permeable to gas and liquid and has a large surface per unit of weight. As safeguard against an excess pressure in the container, the vapor-space of the latter is connected with the external air by safety valves of a sufiiciently wide cross-section.

For the acetylene, those solvents can be used which together with the acetylene do not separate out crystals even at temperatures for below the boiling point of the solution since in most cases such crystals consist of pure acetylene and are of explosive character. As solvents, there can be used, for example, acetaldehyde or acetone either per se or mixed with one another or in mixtures with other ketones and/ or esters, for example with acetic acid ethyl ester.

By a filling having a large surface per unit of weight, a filling is understood which is so loosely piled up or constructed that in comparison with the volume of the material constituting the filling it has a large surface and the said filling material has a low specific weight. Therefore,

the space between the solid parts is very small but in spite of this the ratio between all spaces in comparison with the area occupied by the filling material is very large; As filling material there may be used for example, fine metal wool such as aluminum wool, active carbon, ceramic porous materials or silica-gel.

The protective gas and the filling material must neither react explosion-like with the constituents of the solutionespecially with the acetylene-nor must there be an explosion-like decomposition of possible reaction products or an explosion-like reaction withrthe constituents of the solution. Furthermore, the protective gas is not essentially'to be absorbed by the acetylene solution.

By means of the process according to the invention, it is possible without danger to prepare and to handle an acetylene solution containing about 70 percent by weight and more of acetylene already at the yery low vapor pres- 'sure of approximately atmospheric pressure at a Cortespondmg low temperature. On account of this low presv ice sure, the stationary or portable containers for the acetylene solution need only resist to a corresponding low working pressure of e.g. 1-2 atmospheres gauge pressure-4n special cases to up to approx. 5 atmospheres gauge pressure. Compared with the weight of acetylene, these containers can be comparatively light in structure and the transport of acetylene according to the process of the invention thus requires an essentially lowertare-weight than that necessary according to the processes used up to now.

Of the various characteristics of the invention, the cooling of the solution far below its boiling point under a pressure of 760 millimeters of mercury results in a strongly reduced partial pressure of the vapor above the solution which consists of more than 99% of pure acetylene, i.e. a partial pressure of about 0.2 atmospheres. In order to avoid the penetration of air, the total pressure of the protective gas-vapor-mixture above the solution is at least equal to the atmospheric pressure. Thus, the partial pressure of the protective gas in comparison to the partial pressure of the acetylene can be very much increased and, thereby, the acetylene can be very much diluted with the protective gas. The most serious danger being avoided is that theacetylene and the oxygen cannot explode in the container. Because of the strong dilution of the vaporous acetylene with the protective gas, the gas blown off through the safety valves at the container is already diluted and does not consist of highly concentrated acetylene. In addition, the probability of the decomposition of the acetylene in the container is greatly reduced, i.e. the acetylene vapor above the solution is being desensitized.

By a further characteristic of the invention, i.e. the filling with material permeable to gas and liquid-even though it is present in the vapor-space only in a horizontal uninterrupted layer and fills only partially the said space-a possible decomposition of the acetylene in the vapor-space caused by some outer influence is localized in the vapor-space and, above all, does not endanger the liquid acetylene solution. 1 Since the filling-like a wickin consequence of the capillary forces absorbs the liquid solutions, one would have expected that the acetylene in the sucked up solution would be decomposed, especially in view of the large surface. Unexpectedly, it was found that the solution contained in the filling is by no means aifected in case of a decomposition of the vaporous acetylene. The decomposition is rather restricted to the vapor phasewhile the liquid is completely safe. Apart from aluminum wool, suitable fillings are Raschig-rings, porous ceramic masses and porous coal. I

Furthermore, -by means of sufficiently wide safety valves, the products which are formed by local self-decomposition due to some outer influence and which have a high temperature and large volume are removed quickly and without essential rise in pressure from the container in order to prevent the tearing up of the container-walls which are not constructed for such pressures.

For carrying out the process of the invention, it is advisable to use containers in which the filling is arranged on a sieve or the like in a horizontal layer of even thickness which is in direct contact with the side-walls of the container, the top of the filling lying above the liquid level. In those cases in which free vapor-space remains also below the filling layer, the same is preferably kept much smaller than the upper vapor-space.

To increase thesecurity, the vapor-space can be subdivided into single spaces by partition walls which, if desired, reach into the liquid and whichareinclined towards the liquid-level," preferably in vertical position; feach of the single spaces advantageously being connected with .the atmosphere by a safety valve.

3. upright container (vertical. position)v has. the advantage that the layer of the filling material can be moved downwards pari passu with the falling of the level of the liquid when .the latter is" withdrawn'ythereby; the; requirement to: keep the upper. vapor*space,.in: comparison to the; lower, as large'as possibleissmet-regardless oftheheight of the level;

I Containers-suitablefor use: incarrying outthe process of this invention are: illustratedi diagrammatically bywayof example in theaccompanying drawing of which:

Fig. l is alongitudinalsectionlof apcontainer in hori: zontal position,

Fig; 2' is-a similar view of:the--samezcontainer-with a somewhat different arrangement of the layer of filling material" in addition to dividing walls: fixed in vertical positiontothe longitudinal axis ofithe' container,

Fig.- 3- is a top view of acontainerhaving partition walls parallel and atright angles to the longitudinal axis of the container,- and" Fig. 4 is' a vertical section-of an upright container.

According'to Fig; 1, the container 1 has the shape of a horizontally disposed; cylinder filled with the low-temperature liquid acetylene solution 2 which is to be transv ported or stored. Above the level'3 of the liquid and lying on a screen 4is a layer of filling material 5, Le. aluminum wool, which separates the lower vapor-space 6! from the upper vapor-space 7; The layer isin close contact with the end walls 8 as well aswith the side walls so that apossibleacetylenedecomposition in the upper vapor-space 7 eannotpenetrate around layer 5 intothe lower vapor-space 6" and thus 'into'the' solution 2. The horizontal cross-section ofthe' container 1 is completely filled'by the layer 5"wliichprevents the hot decomposition products from coming into the lower part of the container where they might cause the acetylene to de compose likewise or to' vaporize from the solution with subsequent further decomposition.

I scrapes.

higher acetylene pressures. Other substances with characteristics more or less similar to those of acetylene, e.g. ethylene, no matter whether: at low temperature or ordinary temperature as well as all liquids which produce vapors which are combustible and/or, together with air, form explosive compounds and which have a very high vapor-pressure or low boiling point, as isthe-case'with liquid methane, can be stored in containers for longer or shorter periods. The process according to the invention The upper vapor-space 7 is also provided with a safety valve9 which communicates with the atmosphere. The cross section of this 'valve is such that in case of a possible decomposition, a quick escape of the pressure into the atmosphere readily occurs;

The container 1 illustrated by Fig. 2 difiers' from that of Fig. l in that the layer of fillingmaterial 5 dips into the liquid 2 and a number of' dividing walls 10which also dip into the liquid 2subdividethe vapor-space 7 into a plurality of single areas: Each area has a safety valve 9. This latter feature, however, is not necessary if the dividing walls are" not entirely gas proof so that in caseof an explosion-in oneof the single areasthef pressure canes'cape into the next" area and'through a centrally located valve as shown inFigure' 1.

The container illustratedby Fig. 3 shows even greater subdivision. In addition to the partition walls 10, there are longitudinal walls 11: which cooperate" with the walls 10 to form separated areas. Each area has a safety valve 9. n v

The upright container 12.; as shown in Fig; 4', is, in principle, constructedin the same way as the containers described above. But the cross-section of the container which i'sthe samediameter-throughout permits the moving down of the layer offilling material 5 pari passu with the falling of the level' of the liquid? when. the latter is withdrawn 80111313 thevapor space G'mayremain smaller than the vapor-space" 7, even if container 12 is only partially filled. The downward movement of the filling layer can be carried out by apiston or the like which coversthe layer wholly or partly a'nd'is operated by hand by means of a rod passing through a" gas-tight opening in the container-lid;,the upward movement is caused by the. rising liquid level when the", container, is filled. If desired, the layer of fillingmaterial may, also rest" directly on the liquid like afloating. body and renew theupward amr downward movements. V

The process of the invention'can he applied also at can also be applied with the, same excellent result in all those cases in which solutions or liquids of the aforementioned kind and/or composition are being used in any industrial plant.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

We'claim:

l. A container for storing-and transporting a liquid mixture of acetylene and a solvent under substantially atmospheric'pressure comprisinga closed vessel insulated against the influence oftemperature, a gas and liquid permeable partitioning means separating the container into an upper-protective gas zone and a lower liquid mixture zone, a safety relief valve connecting the upper zone" with the atmosphere and' set at a predetermined pressure above atmospheric pressure and a" layer of porousfilling material'permeableto gas andliquid andhavinga large surface area per unit-of; weight supported by the partitioning means and extending across the entire innercross-sectional area of the container.

2. A- container as set forth in claim 1' wherein the porous filling material completely fills the upper zone.

3. A container as set forth in claim 1 wherein porous fillingmaterial completely fills the lower zone.

41 A container as set forth in claim 1 including means for vertically positioning the partitioning means with respect to change in mixture liquid level.

5; A container as set forth in claim 1 including a plurality of vapor impermeable partitions subdividing the upper zone into individual zones communicating through the partitioning means with the lower zone.

6. A container as set forth in claim 5 wherein a safety relief valve set at a predetermined pressure above atmospheric pressure connects each individual zone with the atmosphere.

References Cited in the file of this patent UNITED STATES PATENTS 928,867 Iames'et al' July. 20,. 1909 996,969 Buckman July 4, 1911 l,5 33',309 D'urburow Apr. 14, 1925 11680;873 Lucas-Girardville Aug. 14, 1928 1,808,900 Luening June 9, 1931 1,930,592 Harnsberger Oct. 17, 1933 2,041,320 Bradley et a1 May 19, 1936 2,148,109 Dana et a1. Feb. 21, 1939 2,525,597 Frazey Oct. 10, 1950 2,543,362 Getz .Feb. 27, 1951 FOREIGN PATENTS 8,010v Great Britain Nov. 19', 1898 err-189s I 23,856 I Great Britain" Feb. 11,, 1911 1 12 5122 Switzerland .i Feb. 1', 19 2 6 335,820 GreatBri'tain Oct. 2, 1930 489. 305 Germany Jan. 16, 1930 OTHER REFERENCES f Eneyclopedia of .Ohe'mifcal r naqm f coma. 1. published by The Interscience Encyclopedia-Incorporated,

N Ybrk. Pages 112-113 relied on. 

